Furthermore, the present invention pertains to a process for determining an absolute position of two bodies in relation to one another, in which a code containing absolute position values of the absolute position is repeatedly scanned and an absolute position signal representative of the absolute position is generated and sent.
Absolute value transducers with measured material elements are generally well known. Physical or three-dimensional absolute positions are determined by these absolute value transducers and represented as absolute position values. In order to be able to determine the absolute position at each point along a measuring path, the measured material elements are designed without gaps. For example, annular measured material elements are placed on shafts to be able to determine their rotational position absolutely. Such a measured material element usually comprises a single continuous code. Absolute value transducers differ from incremental transducers in that they are able to provide the absolute position of the body during switching on, as soon as they are provided with power, at a starting intersection. The detection preferably takes place directly by scanning the code of the measured material element. On the other hand, an incremental transducer does not provide a signal representative of the absolute position, but rather a signal representative of a change in position at a starting intersection.
One-piece measured material elements are not practical especially for determining the actual position of large bodies, for example, of a shaft driving a generator of a wind power plant, since they are very large and can be manufactured and mounted at a high cost only. Furthermore, weight deviations of the shaft cannot be readily compensated with a one-piece measured material element.
Furthermore, measured material elements are difficult to manufacture for irregular measuring paths. For example, to produce motions of the body along a measuring path that is composed of translational and/or rotational motions, a corresponding measured material element, which is possibly of an irregular shape, should be manufactured in one piece. A manufacture of such a measured material element is very susceptible to manufacturing tolerances, however.